That's Yui's line in Ep.12, below is its subtitles from [HorribleSubs].
"But one day, I saw two players whose mental parameters were very different than the rest."

So this is the true reason?

Joy, peace, and sex.

That is so amazing

theres a reason why Yui is their love-child...

nearly fell off my seat laughing my ass off, this is definitely going in the Perversion of Canon pool